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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: Remotely Controlled Manipulators in Space
Message-ID: <8602020218.AA04732@s1-b.arpa>
Date: Sat, 1-Feb-86 19:40:10 EST
Article-I.D.: s1-b.8602020218.AA04732
Posted: Sat Feb  1 19:40:10 1986
Date-Received: Mon, 3-Feb-86 06:30:47 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 39

The Challenger explosion has got me thinking about more about
teleoperated mechanical manipulators for space tasks.  These are robot
arms or similar devices controlled from Earth by humans.  Such devices
already exist on Earth as manipulators on submarines and for handling
radioactive substances.   The problem with using them in space is the
nonnegligible feedback delay imposed by the speed of light: about .25 to
.3 seconds for geosynchronous orbit and about ten times that for the moon.

There are lots of interesting questions raised by these machines.  How
inconvenient is the feedback delay?  What kind of force sensing is
needed to prevent the manipulator from crushing things?  What kind of
sensors should the manipulator have?  Cameras, surely, but how many
and what kinds?  How much image processing should be done, and how
a should the resulting information be presented to the operator?  Where
should the processing be done: in space or on the ground?

The remote manipulators would have many uses, and would probably be
built with interchangable effectors for various missions.  Suggested
missions include: satellite refueling and/or part replacement in
geosynchronous orbit, lunar mining and manufacturing, and
orbital manufacturing of habitats or solar power collectors.
Gerard K. O'Neill estimates that, using remotely controlled
manipulators, a "seed" manufacturing facility capable of
making 1800 tonnes of material per year could be put in place
with 107 tonnes on the moon and 89 tonnes in high orbit.  The facility
would be capable of reproducing itself (except for some "vitamins",
like integrated circuits and some volatiles) in 90 days.

Remotely controlled manipulators probably also make sense even if
humans are in orbit.  For example, it probably would be more efficient
(and safer) for the human to be close (< .05 light seconds) to the
manipulator (and inside a habitat) than for the human to be in a space
suit.

A study of the effect of feedback delays on manipulator performance
would seem to be an excellent research area for a robotics lab.  This
research would probably be the single most important near term
contribution a computer scientist/roboticist could make to the space
program.